Question: Which is the battle that participated the Soviet Union?
SPARQL (Wikidata):  select distinct ?sbj where { ?sbj wdt:P710 wd:Q15180 . ?sbj wdt:P31 wd:Q178561 } 
Answer: Battle of Smolensk, Battles of Khalkhin Gol, Battle of Prokhorovka, Battle of Debrecen, Battle of Radzymin, Second defensive battle at the Don, Battle for Narva (1944), Battle of Surkonty, Battle of Stalingrad